Side gripper for square bottomed paper bag forming machines



A o SOHN 2,450,309

Sept. 28, 1948. SIDE GRIPPER Foa SQUARE BoTToMED PAPER BAG FORMING MACHINES f Filed Jan. 9, 1947 2 Sheets-Sheet 1 Sept. 28,' 1948. A o, SOHN l 2,450,309

SIDE GRIPPER FOR sQUA RE oTToMED PAPER BAG FORMING MACHINES 2 Sheets-Sheet? Filed Jan. 9, 194'? atented Sept. 28, 1948 NETED STATES PATENT OFFICE SIDE GRIPPER FOR SQUARE BOTTOMED PAPER BAG FORMING MACHINES Allen O. Sohn, Plymouth, Wis. Application January 9, 1947, Serial No. 721,046

2- Claims.

This invention relates to improvements in paper bag machines and refers particularly to machines of the type illustrated in Patent No. 1,571,983, issued to H. G. Weber, on February 9, 1926. Bags made on the machine of the Weber patent are of the so-called automatic or selfepening type in which the bottom is square and the sides of the bag, during the formation there-- of, are provided with tucks.

During the formation of the bottom the blank from which the bag is made passes between upper and lower cylinders or'drums which carry mechanism to act upon the blank in the formation of the bottom. Included in this mechanism are side grippers mounted on the cylinders or drums in such a Way that the side grippers on the upper cylinder or drum engage over the side edges of the upper tuck while those on the lower cylinder or drum engage over the side edges of the lower tuck to thus open the tucks as the grippers on the cylinders or drums move away from each other.

In addition to opening the tubular blank in preparation to the formation of the bottom the side grippers also serve as guides to locate the corner folds of the bottom. For this purpose the work engaging portions of the grippers are cut at an angle to lie diagonally across the edge portion of the tuck grasped by the gripper. The location at which the side grippers engage the blanks with respect to the side edges of the blanks, is thus highly important as any variation from the correct location affects the size of the bag formed.

The setting of the grippers with respect to the surface of the cylinder or drum is also critical. While the grippers engage the blanks with a spring pressure, this pressure must be uniform and not too severe. Hence, the grippers are set with a predetermined clearance, generally a few thousandths of an inch, between the claw or paper engaging portions thereof and the surface of the cylinder or drum.

The maintenance of the proper setting and location of the grippers in the face of the inevitable and substantial wear to which they are subjected has been a serious and troublesome problem in the past.

The means heretofore employed for adjusting the side grippers in an effort to maintain proper setting and location as shown in the aforesaid Weber patent entails rotation of eccentrically mounted shafts on which the grippers are pivoted. While this expedient enables adjusting the claw cr paper engaging fingers of the grippers toward and from the surface of the drum, it also shifts 2 the location of the fingers transversely of the drum, which, as pointed out, is highly objectionable once the location for a particular bag size has been set.

Moreover, the side grippers, especially those on the lower drum, are so located that access thereto is difficult. Their eccentric mounting shafts are particularly hard to get at. Consequently, the operators of the machines shun adjustment of the side grippers with the result that the quality of the Work suffers.

The present invention contemplates the elimination of the difficulties and disadvantages inherent in the past constructions and to this end has as an object to provide a simple means for adjusting the claw or paper engaging portions of the grippers, which is so located as to be readily accessible and which is so designed that the adjustment of the clearance between the nger and the drum in nowise involves shifting the location of the fingers transversely of the drum.

Another object of this invention is to provide an improved side gripper of the character described wherein the active paper engaging finger portion thereof is readily removable to enable the same to be easily replaced when it has become too badly worn.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the herein disclosed invention may be made as come within the scope of the claims, f

The accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed in accordance with the best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a sectional view through the lower cylinder or drum of the bottom forming mechanism in a paper plication of this invention thereto;

Figure 2 is a side View of a portion of the structure shown in Figure 1;

Figure 3 is a perspective view of a portion of the cylinder or drum to more clearly illustrate the position of the side grippers thereon; and

Figure 4 is a perspective View of the claw or paper engaging portions of the grippers,

As noted hereinbefore, this invention is concerned chiefly with the so-called side grippers which form part of the bottom forming mechabag machine illustrating the ap.

nism of paper bag machines such as illustrated in the aforementioned Weber Patent No. 1,571,983. inasmuch as the invention does not concern itself with the general construction of the bag machine. no attempt has been made to illustrate the same except to the extent necessary to show the application of this invention thereto. For additional disclosure of the machine, reference may be had to the aforesaid Weber patent.

As shown in said patent, the bottom forming mechanism includes cooperating upper and lower cylinders or drums, the latter being three times the size of the former. These drums rotate in op-V posite directions and have the same peripheral speed. Side grippers of the type with which this invention is concerned coact with each drum. The smaller upper drum has but one such gripper at each side while the larger lower drum has three on each side, if as stated, the lower drum is three times the diameter of the upper drum.

The construction of the grippers used on the two drums may be the same, but in View of their inaccessibility this invention is concerned chiey with the grippers of the lower drum. Hence the drawing, to which reference is now specifically made, illustrates only the lower drum, and for that matter only that portion thereof required to show the application of the side grippers of this invention thereto.

Referring now particularly to the accompanying drawings in which like numerals indicate like parts, the numeral 5 designates generally the lower drum of the bottom forming mechanism of a bag machine of the type described. This drum is mounted upon a shaft 6 which is journalled in the side frames of the machine, not shown. At each side of the cylinder or drum 5 is a hub 'i slidably splined to the shaft 6. A spider 3 is secured to each of the hubs 1 by means of cap screws 9 or the like. The screws 9 pass through elongated arcuate slots in the hub members i to allow the spiders to be adjusted angularly with relation to the drum or cylinder. Each spider il has three radially diverging arms (only one being shown) and the outer ends of these arms re bifurcated to receive the body II of a gripper indicated generally by the numeral I2. A pin I3 pivotally mounts the body I I on the bifurcated arm IG.

Projecting radially outwardly from the gripper body Il is a substantially rectangular extension le. A claw or gripper finger indicated generally by the numeral I5 is adjustably secured to this extension by means of a clamping screw I6.

This claw or gripper finger as best shown in Figure 4 is preferably stamped from sheet metal and is generally angular in shape with one leg i8 thereof channel shaped in cross section to embrace the extension I4, while the other leg I9 is substantially flat and of a size to overlie the edge of a gap 5 in the drum or cylinder 5. A down struck teat or projection 2l on the leg I9 provides a paper engaging pad of relatively small area to insure a rm grip on the portion of the bag blank under it.

The pivot pin i3 is an ordinary pin, all portions of which are concentric so that no adjustment of the body II such as that employed in the aforesaid Weber patent exists in this case. The adjustment of the gripper to compensate for wear is effected by the simple expedient of having the connection between the claw or gripper finger and the extension i4 adjustable. To this end the screw i6 which is threaded into the extension passes through an elongated slot 22 in the leg I3 4 of the claw or finger. The side flanges of this leg embracing the extension hold the claw or finger against rotation about the screw.

In View of the fact that the screw I6 is readily accessible, proper adjustment of the claw or finger I5 is a simple matter. Likewise, if it is found that the claw or nger is worn too badly it may be quickly and easily replaced with a new one. Moreover, the way in which the adjustment is here achieved, in nowise disturbs the position of the claw or linger transversely of the drum.

The manner in which the grippers are actuated, that is, opened and closed is substantially the same as described in the Weber patent. Hence the description thereof which follows need not be too detailed.

It is sufcient to point out that the body II of the gripper has-a lever 23 pivoted thereto as at 24. The upper end of this lever, which lies between two walls jutting out from the body II, bears against a spring 25 interposed between it and the bottom of a socket in the body II. Hence, upward or radially outward force applied to a cam follower 26. mounted on a pin xed to the lever 23 compresses the spring 25 to urge the body of the gripper in a direction to bring its claw down onto the adjacent tuck of a bag blank on the drum.

Inasmuch as the pressure with which the claw bears down on the paper must be uniform and not too severe, the cam produced motion of the gripper body is limited by a lug 28 on the body colliding with the side of the spider arm I0. The adjustment of the claw or nger I5 is such that when the gripper body is in the position dened by the stop lug 28', its pad or teat 2| is a few thousandths of an inch from the surface of the drum which it overlies. The extent of this clearance is determined by the character of the paper and must be such that the paper will be held firmly but without making anobjectionable im.- pression therein.

A tension spring 29 at all times yieldingly urges the gripper to open position and causes the cam follower to ride on a cam 30. The contour of the cam 30 thus determines when the gripper is closed and opened, and as the cam need not be continuous, another stop lug 21 on the gripper body limits the spring produced retraction of the gripper, by colliding with the spider arm I0.

Attention is directed to the fact that the range of motion of the gripper is relatively slight, being approximately six degrees. Hence adequate clearance between the claw or gripper flnger and the drum surface it overlies is obtained by slightly relieving the underside of the claw or finger laterally outwardly fromits pad or teat 2 I.

The entire gripper assembly is adjustable axially of the shaft 6 (i. e. laterally of the machine) by sliding the hub l' along 4the shaft 6, but the cam 30 is stationary. To allow for this adjustment of the gripper assembly the face of the cam is wide as shown. In this respect the present construction is more advantageous than that of the aforesaid Weber patent wherein the gripper controlling cam occupies a plane normal to the axis of the shaft rather than parallel thereto, making it impossible to adjust the gripper assemblylaterally to accommodate different width bags.

Though not strictly essential to a description of the present invention, it may be helpful to point out that the leading end of the tubular blank has a lip L by which the blank is held to the drum 5 (see Figure 3) at the time the side grippers move into the side tucks T of the blank. Attention is also directed to the fact that the drum has a hardened steel insert 33 at the edge' 20 of the gap 5 which accommodates the grippers, and that this insert provides the surface against which the claws or fingers of the grippers clamp the blank with the diagonal edge 34 of the claws or ngers positioned to provide a guide or anvil over which the blank is folded during the formation of the bottom. The gap 35 in the face of the drum accommodates tucking blades not shown, and of course other mechanism also not shown operates in the gap 5'.

From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent to those skilled in this art, that this invention provides an extremely simple manner of obtaining the necessary adjustment in the side grippers of a paper bag machine and that it likewise permits quick and easy replacement of Worn grippers and enables bodily adjustment of the gripper assembly laterally of the machine to accommodate bags of different widths.

What I claim as my invention is:

1. In a bag forming machine having a drum mounted on a shaft and on which the bag blank is held during the formation of the bottom of the bag, said drum having a gap in the face thereof at least one edge of which is parallel with the drum axis, a side gripper for holding a portion of the blank to the drum at said edge of the gap, comprising: a hub slidable on the drum shaft and rotatable therewith; a gripper body; a pivotal support for the gripper body carried by the hub, constraining the gripper body to pivotal movement about an axis at all times normal to and spaced from the drum axis and perpendicular to a line radial to the drum axis while enabling movement of the gripper body with the hub axially of the drum; a gripper claw; a connection between the gripper claw and the gripper body guiding relative motion therebetween along a line radial to the drum axis, said claw extending through the gap in the drum and having a part overlying said edge of the gap at a point along the length thereof determined by the axial position of the hub on the drum shaft; and means for adjustably and removably securing the claw to the gripper body.

2. In a paper bag machine having a drum on which bag blanks travel and are held during the formation of the bottom of the bag, said drum having a gap therein at least one edge of which is parallel to the drum axis, a gripper for holding a portion of the blank to the drum, comprising: a gripper body; a support for the gripper body adjustable axially of the drum; means pivotally mounting the gripper body from said support with the gripper body pivotal about an axis normal to the drum axis but shiftable axially of the drum by adjustment of said support; a gripper claw; means readily removably securing the claw to the gripper body with the claw projecting through the gap in the drum and overlying said edge of the gap at a point determined by the position of the gripper support axially of the drum; a gripper actuating cam having a wide cam surface all parts of which are parallel with the drum axis; anda cam follower connected with the gripper body and riding on said cam in all positions of adjustment of the gripper assembly axially of the drum.

ALLEN O. SOHN.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date *0 1,571,982 Weber Feb. 9, 1926 2,324,358 Burroughs July 13, 1943 

